Third generation mobile systems (3G), based on WCDMA (Wideband Code Division Multiple Access) radio access technology, are being deployed on a broad scale all around the world. However, as user and operator requirements and expectations will continue to evolve a new phase in the project called 3rd Generation Partnership Project (3GPP) has started to consider the next major steps in the evolution of the 3G standard. The terminals used in the network are having more functions integrated which means that an increasing number of access types such as e.g. LTE (Long Term Evolution), WiMAX (Worldwide Interoperability for Microwave Access) and WLAN (Wireless Local Area Network) and new services such as Voice over IP (VoIP) or IP-TV are added to the terminal. This has the implication that there is a need for support from the network to guide the terminal regarding which access to select. The terminal is henceforth in the description and claims called a User Equipment, UE.
In the technical specification 3GPP TS 23.203 v7.3.0, release 7, a new architecture for Policy and Charging Control (PCC) is introduced and the different functions are specified. The PCC architecture is illustrated in FIG. 1. The functions in FIG. 1 are, according to this specification, defined as follows.
The main parts of the PCC architecture consists of an Application Function (AF), 101, a PCRF (Policy and Charging Rules Function), 103, a Subscription Profile Repository (SPR), 107 and a PCEF (Policy and Charging Enforcement Function), 105. These parts are shown in FIG. 1. The PCC also includes an Online Charging System (OCS) connected to the PCEF through a reference point Gy and an Offline Charging System (OFCS) connected to the PCEF through a reference point Gz. The OCS and OFCS are not shown in FIG. 1 as they are not of primary interest for the invention.
The Application Function (AF) 101 is an element offering applications the possibility to request resource allocation, via the PCC, in the network such as e.g. Universal Mobile Telecommunication System (UMTS) Packet Switched (PS) domain or General Packet Radio Service (GPRS) domain resources. One example of an application function is a P-CSCF (Proxy—Call Session Control Function). The P-CSCF is a SIP (Session Initiated Protocol) proxy server which is the first point of contact for an IMS (IP Multimedia Subsystem) User Equipment.
The AF 101 use an Rx reference point 102 to provide session information to the PCRF (Policy and Charging Rules Function) 103. The signalling flow between the AF 101 and the PCRF 103 through the Rx reference point 102 is specified in 3GPP TS 29.213 v7.0.0. More detailed information regarding the PCC over the Rx reference point is specified in 3GPP TS 29.214 v7.0.0.
The PCRF 103 is a functional element that encompasses policy control decision and flow based charging control functionalities. These 2 functionalities are the heritage of the 3GPP release 6 logical entities PDF (Policy Decision Function) and CRF (Charging Rules Function) respectively. The PCRF provides network control regarding the service data flow detection, gating, QoS (Quality of Service) and flow based charging (except credit management) towards the PCEF (Policy and Charging Enforcement Function). The PCRF receives session and media related information from the AF and informs the AF of traffic plane events.
A Gx reference point 104 is located between the PCRF and the PCEF. The Gx reference point is used for provisioning and removal of PCC rules from the PCRF to the PCEF and the transmission of traffic plane events from the PCEF to the PCRF. The stage 2 level requirements for the Gx reference point are defined in 3GPP TS 23.203 v7.3.0, release 7.
Signalling flows between the PCRF and the PCEF through the Gx point 104 is specified in 3GPP TS 29.213 v7.0.0. More detailed information regarding the PCC over the Gx reference point is specified in 3GPP TS 29.212 v7.0.0.
The PCC contains a number of rules defining how to treat received data packages. The purpose of a PCC rule is to:                Detect a packet belonging to a service data flow.                    The service data flow filters within the PCC rule are used for the selection of downlink IP-CAN (Internet Protocol Connectivity Access Network) bearers. An IP-CAN bearer is an information transmission path of defined capacity, delay, bit error rate e.t.c. When using GPRS (General Packet Radio Service) the IP-Connectivity Access Network (IP-CAN) bearers are provided by Packet Data Protocol (PDP) contexts.            The service data flow filters within the PCC rule are used for the enforcement that uplink IP flows are transported in the correct CIP-AN bearer.                        Identify the service the service data flow contributes to.        Provide applicable charging parameters for a service data flow.        Provide policy control for a service data flow.        
The PCEF shall select a PCC rule for each received packet by evaluating received packets against service data flow filters of PCC rules in the order of the precedence of the PCC rules. When a packet matches a service data flow filter, the packet matching process for that packet is completed, and the PCC rule for that filter shall be applied.
There are two types of procedures for activation of rules:                Rules activated at IP-CAN establishment/modification/deactivation.        Rules activated/modified/deactivated at application session setup/modification/deactivation.        
A PCC rule consists of:                a rule name;        service identifier;        service data flow filter(s);        gate status;        QoS parameters;        charging key (i.e. rating group);        other charging parameters.        
The PCEF is the functional element that encompasses policy enforcement and flow based charging functionalities. These 2 functionalities are the heritage of the 3GPP release 6 logical entities PEP (Policy Enforcement Point) and TPF (Traffic Plane Function) respectively. This functional entity is located at a Gateway 106 e.g. a Gateway GPRS Support Node (GGSN) in the GPRS (General Packet Radio Service) case. It provides control over the user plane traffic handling at the Gateway and its Quality of Service (QoS), and provides service data flow detection and counting as well as online and offline charging interactions.
For a service data flow that is under policy control the PCEF shall allow the service data flow to pass through the Gateway 106 if and only if the corresponding gate is open.
The Subscription Profile Repository function (SPR) 107 contains all subscriber/subscription related information needed for subscription-based policies and bearer level charging rules by the PCRF. The SPR may be combined with other databases in the operator's network.
The Sp reference point 108, between the SPR and the PCRF, allows the Subscription Profile Repository (SPR) to provide subscription-based input to the PCRF. The Sp reference point allows the PCRF to request subscription information related to bearer level policies from the SPR based on subscriber ID. The subscriber ID can e.g. be IMSI (International Mobile Subscriber Identity). The reference point allows the SPR to notify the PCRF when the subscription information has been changed if the PCRF has requested such notifications.
In the 3GPP TS 23.203 v7.3.0, release 7, PCC architecture the PCRF has got a passive role in the access selection procedures. At IP-CAN establishment the Radio Access Technology (RAT) type is sent to the PCRF. The PCRF is able to reject the IP-CAN establishment e.g. in case the RAT type is not according to the user's profile. The PCRF has no active role in the selection of the access type. The decision of what access to use within one access type (e.g. 2.5 G vs. 3G) is typically controlled via interactions between the UE and the radio network. The decision, about which access types to select, if there are multiple access types (e.g. WLAN and WCDMA) available, is today mainly controlled by the UE.
With the existing solution there is no mechanism available that can enable control from the network regarding which access type to select. The selection of access type is primarily controlled by the UE.
This means that there are limited possibilities in prior art solutions of today for the network provider to control the access selection and guide the user to a certain access e.g. in order to:                Optimize the network load by suggesting the UEs to use the most cost effective access type when the UE is in e.g. a hot spot area.        Control that the UE uses the access type that is most appropriate for the application.The current PCC architecture can handle several parallel IP-CANs for the same UE but the architecture demands that each IP-CAN is treated individually. This means that there is no place in the network with a full control of all active accesses for one user. This also means that there are limited possibilities for the network to orchestrate between the different accesses.        